A shuttle valve of this type is already known; FIG. 1 shows such a known valve.
Such shuttle valves make possible the change-over of a conduit to one of two further conduits, the most frequently used being the combination with safety devices, as FIG. 16 renders schematically. There such a shuttle valve 10 is provided on a gas container 250 under pressure for example in order to produce alternatively a flow path to a first or a second safety valve 251, 252 in such a way that one valve is always ready to operate while the second serves as a stand-by valve. Behind the safety valves the flow branches can be joined again by means of a further shuttle valve 253 in order to create a single outlet 254 for the gas.
A shuttle valve should always be open in one direction and should hinder the flow of flow medium as little as possible. The latter is not the case in the embodiment illustrated in FIG. 1 in accordance with the prior art as a very sharp turn in the flow occurs which can lead to a considerable pressure drop as a result of high flow resistance. A further disadvantage is that if the known shuttle valve is not used properly the valve can also assume a permanent intermediate position in which flow medium can flow into both branches of the shuttle valve. This shuttle valve can then be used wrongly. Moreover it is inconvenient that in order to change over the shuttle valve according to FIG. 1 many turns of the handwheel illustrated there are necessary. This is not only time consuming but it also prevents a completely synchronous operation of several shuttle valves, e.g. the two shuttle valves 10, 253 illustrated in FIG. 16.
It should moreover be ensured that in both directions of flow the exact same conditions are present which is not necessarily the case in the embodiment according to FIG. 1 because of the asymmetrical construction of the slide 20 with regard to the two branches 16, 18.
The shuttle valve 10 is certainly described as having one inlet connecting piece and two outlet connecting pieces, however the direction of flow should on principle be able to be chosen freely. In the case of the second shuttle valve 253 according to FIG. 16 the direction of flow is such that both "outlet connecting pieces" serve as an inlet for flow medium while the "inlet connecting piece" serves to discharge the flow medium. "Inlet" and "outlet" are interchangeable in this respect.
FIG. 2 shows an improved construction vis a vis FIG. 1 by which, albeit in a rather complicated manner, is achieved, that the valve disc is rotatable axialsymmetrically with regard to the two branch conduits, moreover the actuation shaft is only to be twisted by 180 degrees, after a locking device has lifted the valve disc off the valve seat, whereupon the valve disc rotates by 180 degrees and then, through appropriate actuation of the locking device, is driven back on to the valve seat, this time of the other branch. This arrangement results in very costly treatment of inner parts for turning mechanisms. The assembly is also very expensive.
The aim of the invention is to improve the known shuttle valve so that there is only a very slight flow resistance and so that a change-over is possible when the spindle or shaft is turned by less than 360 degrees without a special locking device having to be actuated separately and that, without complicating the construction according to the prior art too much, a considerably simpler and safer, maloperation reducing construction is created which can also be operated by remote control if need be.